The present invention relates to data storage systems, and more particularly, this invention relates to a tape-based data storage system having an actuator configuration for tape skew compensation.
In magnetic storage systems, magnetic transducers read data from and write data onto magnetic recording media. Data is written on the magnetic recording media by moving a magnetic recording transducer to a position over the media where the data is to be stored. The magnetic recording transducer then generates a magnetic field, which encodes the data into the magnetic media. Data is read from the media by similarly positioning the magnetic read transducer and then sensing the magnetic field of the magnetic media. Read and write operations may be independently synchronized with the movement of the media to ensure that the data can be read from and written to the desired location on the media.
An important and continuing goal in the data storage industry is that of increasing the density of data stored on a medium. For tape storage systems, that goal has led to increasing the track and linear bit density on recording tape, and decreasing the thickness of the magnetic tape medium. However, the development of small footprint, higher performance tape drive systems has created various problems in the design of a tape head assembly for use in such systems.
In a tape drive system, the drive moves the magnetic tape over the surface of the tape head at high speed. Usually the tape head is designed to minimize the spacing between the head and the tape. The spacing between the magnetic head and the magnetic tape is crucial and so goals in these systems are to have the recording gaps of the transducers, which are the source of the magnetic recording flux in near contact with the tape to effect writing sharp transitions, and to have the read elements in near contact with the tape to provide effective coupling of the magnetic field from the tape to the read elements.
The quantity of data stored on a magnetic tape may be expanded by increasing the number of data tracks across the tape. More tracks are made possible by reducing feature sizes of the readers and writers, such as by using thin-film fabrication techniques and magnetoresistive (MR) sensors. However, for various reasons, the feature sizes of readers and writers cannot be arbitrarily reduced, and so factors such as tape skew, lateral tape motion (e.g., perpendicular to the direction of tape travel), transients and tape lateral expansion and contraction must be balanced with reader/writer sizes that provide acceptable written tracks and readback signals.
One issue limiting areal density is misregistration caused by tape skew. As tape is being run over the surface of a tape head, angular shifts in the relative angular relationship between an array of transducers and the data tracks on the tape may occur. Accordingly, data may not be readable from a tape, particularly as the tape capacity increases over time and tracks become smaller.